EP2920076B1 - Air conditioning method and system for aircraft - Google Patents

Description

FIELD OF THE INVENTION

The invention relates to the field of air conditioning in aircraft and more particularly to the conditioning of air intended for feeding the pressurized cabin of an aircraft. The invention more particularly relates to an air conditioning system and method for an aircraft and an aircraft comprising such a system. Examples of the prior art are provided by the documents EP2165931 and US2012 / 0240599 .

STATE OF THE ART

At cruising altitude of an aircraft, for example at an altitude of 10,000 meters, the pressure of the ambient ambient air is, in general, approximately 0.2 to 0.3 bar and its temperature between - 20 and -60 ° C while the pressure in the pressurized cabin of the aircraft is about 0.8 bar and the input temperature of the air conditioning module of the cabin of about -15 ° C.

In order to supply the pressurized cabin with air, it is known to draw air from the main engines in order to condition it and then convey it to an air conditioning module of the cabin.

A flow of compressed air, at high pressure and temperature, is thus taken from the compressor stages of the main engines and is then cooled through a pre-cooler (pre-cooler in English) at the outlet of which its pressure is about 2 bar and its temperature of about 200 ° C. This air is then cooled again and both dried and expanded in a cooling module at the outlet of which its pressure is close to that of the cabin, about 0.8 bar, and its temperature is about -15 ° C. . The air thus conditioned is then conveyed to the air conditioning module of the cabin of the aircraft to ensure the thermal regulation and the supply of fresh air. Such a system, however, has several disadvantages.

Firstly, the pressure of the air taken is high, the air must be depressed so as to reach the required pressure level at the entrance of the air conditioning module of the cabin of the aircraft. Such relaxation requires the use of a cooling module comprising a turbocharger and a plurality of heat exchangers who consume energy and complexify the structure of the system, which presents a first disadvantage.

In addition, the pre-cooler of such a system requires additional air withdrawal, at low temperature, to cool the hot air taken from the compressor stages of the main engines of the aircraft. Such a multiplicity of air samples at different locations of the aircraft complicates the air conditioning system and therefore the internal structure of the aircraft, which increases the drag and the fuel consumption and has a second disadvantage.

Such a system also makes the installation and operability of the main engines more complex and can reduce their performance, which presents a third disadvantage.

Furthermore, the intake of air at the compressor stages of the main engines decreases the amount of usable air for the propulsion of the aircraft, which increases the fuel consumption and therefore has a fourth disadvantage.

Finally, the variability of the engine speed imposes a complex system to ensure an invariable minimum level of air sampling, which presents a fifth drawback.

STATEMENT OF THE INVENTION

The invention aims to improve the existing air conditioning systems for aircraft so as to save the energy of the aircraft and simplify the air conditioning and more generally the aircraft structure.

Thus, the invention relates to an air conditioning system for a pressurized cabin of an aircraft according to claim 1.

By the term "outside ambient air" is meant free air outside the aircraft, as opposed to air circulating in the engines of the aircraft.

The air thus cooled can then be conveyed to an air conditioning module of the cabin of the aircraft which will then adjust the temperature of the air flow according to the cabin settings to supply it with air fresh.

The compression module compresses the ambient air taken from the outside of the aircraft, the pressure and temperature of which are generally below the pressure and temperature levels required at the entry of the air-conditioning module of the cabin. Such compression makes it possible to increase the pressure of the air up to the required pressure level in the cabin, for example 0.8 bar. Since the pressure of the outside ambient air taken is of the order of 0.2 or 0.3 bar, the compression ratio associated with such compression to obtain a pressure close to the level required in the cabin, for example 0.8 bar is low, for example of the order of 3 or 4, and therefore requires little energy. The compression can be performed up to a value slightly greater than the pressure required in the cabin, for example 0.9 bar, so as to provide for the decrease in air pressure due to the pressure drops between the compression module of the cabin. air and the air conditioning module of the aircraft.

When the compression increases the temperature of the air drawn beyond the input level of the cabin air conditioning module, the cooling module receives and then cools the flow of compressed air to the required input temperature level. the air conditioning module of the cabin, for example -15 ° C. The cooled air is then supplied to the air conditioning module of the aircraft to provide thermal regulation and the supply of fresh air to the pressurized cabin of the aircraft .

The system according to the invention takes only ambient ambient air. It is therefore no longer necessary to draw air at the compressor stages of the main engines, which makes it possible to improve its efficiency and to make the air conditioning system independent of variations in the engine speed of the engine. the aircraft. In particular, and contrary to existing solutions, the air sampling module of the system according to the invention can thus comprise a single air sampling means which can consist, for example, of a dynamic air inlet or good of a controllable valve.

In addition, it is no longer necessary to multiply the air samples at different temperatures and at different locations on the aircraft, which simplifies the architecture and reduces the drag and therefore the fuel consumption.

The structure of such a system is simple and allows in particular to avoid the use of a turbocharger and a plurality of heat exchangers for cooling the air. The installation, operability and maintenance of the engines are furthermore made easier.

The cooling fluid storage means are thus easily refillable, for example, during the maintenance of the aircraft. Such a cold accumulator makes it possible to reduce the temperature of a first flow of air without the need to take a second flow of ambient ambient air. In addition, the air is compressed to the required value in the cabin or slightly above it to compensate for pressure losses in the system, significantly limiting the energy required for this compression, the cooling is obtained without relaxation. of air, which simplifies the structure of the system by avoiding the use of a relaxation module.

Preferably, the cooling module is autonomous. The term "autonomous" means that the cooling of the air is carried out solely by means of the cooling fluid stored in the storage means, that is to say without using fluid from another source.

According to one characteristic of the invention, the cooling fluid storage means are configured to store a low temperature fluid, for example less than -180 ° C, for cooling the flow of compressed air.

According to one characteristic of the invention, the cooling fluid is a cryogenic fluid, preferably a cryogenic liquid.

According to one characteristic of the invention, the cooling fluid storage means are in the form of a cryogenic fluid reservoir. Such a cryogenic fluid may, for example, be liquid nitrogen, liquid air, liquid helium, etc.

Advantageously, the cooling module is configured to deliver a gaseous fluid, for example nitrogen gas under pressure, preferably the temperature is lower than that of the flow of compressed air, can feed a turbine and thus provide mechanical energy.

According to one aspect of the invention, the system comprises a heat exchange module, for example a heat exchanger, arranged between the air compression module and the cooling module, configured to cool the flow of compressed air, received from the air compression module, from the flow of gaseous fluid delivered by the cooling module, and convey, on the one hand, the flow of compressed air thus cooled to the cooling module and on the other hand , the flow of gaseous fluid to a heating module. Such a loop makes it possible to use the caloric energy of the gaseous fluid delivered by the cooling module in order to carry out, through the heat exchanger, a pre-cooling of the flow of compressed air.

According to one aspect of the invention, the system comprises an air flow orientation module disposed between the compression module and the cooling module and configured to guide the flow of air, compressed by the compression module. to the air cooling module, when the temperature of the compressed air is higher than the required temperature at the inlet of the air conditioning module of the cabin, or to a heating module, when the temperature of the air Compressed air is below the required input temperature of the cab air conditioning module.

Preferably, the orientation module of an air flow is in the form of a two-way valve.

More preferably, the system comprises a heating module configured to receive a flow of gaseous fluid to be heated, for example, from the heat exchange module or a flow of air from the orientation module of a flow of heat. 'air.

According to a characteristic of the invention, the heating module is configured to route the heated air to the air conditioning module of the cabin or to a turbine.

Advantageously, the system comprises a turbine configured to receive, from the heating module, the flow of gaseous fluid and to supply, for example, a generator to produce electric current, for example, to supply Aircraft equipment. The outgoing flow of such a turbine may also make it possible to cool the engine bay or bays of the aircraft (an engine bay being the enclosure in which an engine is installed), and / or to render the atmosphere inert, thus greatly reducing the risk of fire. The recovery of the gaseous fluid delivered by the cooling module thus makes it possible to produce additional energy at low cost.

Preferably, the compression module is a charge compressor, for example an auxiliary power unit (APU, Auxiliary Power Unit in English).

According to one characteristic of the invention, the cooling module comprises a condenser configured to condense the water of the air flow, a water extractor configured to extract said water, a cooler configured to cool the flow of dry air and a reservoir of a cooling fluid, for example a cryogenic liquid such as liquid nitrogen, liquid air, liquid helium, etc., configured to allow condensation of the flow water by the condenser and the cooling of the dried flow by the cooler, for example to negative temperatures without risk of clogging by frost.

Advantageously, the cooling module is configured to dehumidify the flow of compressed air received.

According to one characteristic of the invention, the heating module is a heat recovery unit, for example a heat exchanger.

The invention also relates to an aircraft comprising an air conditioning system as defined above.

• une étape de prélèvement d'air ambiant extérieur à l'aéronef,
• une étape de compression du flux d'air prélevé,
• une étape de refroidissement du flux d'air comprimé par un fluide cryogénique,
• une étape d'acheminement du flux d'air ainsi refroidi vers le module de climatisation de la cabine de l'aéronef.

The invention also relates to a method of air conditioning in an aircraft as defined above comprising a pressurized cabin and an air conditioning module of said cabin, said method being remarkable in that it comprises:

• a step of taking ambient air outside the aircraft,
• a step of compressing the air flow taken,
• a step of cooling the flow of compressed air by a cryogenic fluid,
• a step of conveying the air flow thus cooled to the air conditioning module of the cabin of the aircraft.

Preferably, the method comprises, between the compression and cooling steps, a step of directing the air flow, compressed by the air compression module, towards the air cooling module, when the temperature of the air the compressed air is higher than the required input temperature of the cabin air conditioning module, or to a heating module, when the temperature of the compressed air is below the required temperature at the inlet of the cabin air conditioning module .

According to one aspect of the invention, the method further comprises a step of sending, by the heating module, a flow of gaseous cooling fluid to a recovery turbine.

• la figure 1 représente schématiquement le système de conditionnement d'air selon l'invention ;
• la figure 2 représente schématiquement le module de refroidissement du système de la figure 1 ;
• la figure 3 illustre le procédé de conditionnement d'air selon l'invention.

Other features and advantages of the invention will become apparent from the following description made with reference to the appended figures given by way of non-limiting examples and in which identical references are given to similar objects:

• the figure 1 schematically represents the air conditioning system according to the invention;
• the figure 2 schematically represents the cooling module of the system of the figure 1 ;
• the figure 3 illustrates the air conditioning method according to the invention.

DETAILED DESCRIPTION

In an aircraft, the air conditioning system is used to supply air to the pressurized cabin from outside air.

DESCRIPTION OF THE SYSTEM ACCORDING TO THE INVENTION

The embodiment of the air conditioning system 1 according to the invention illustrated in FIG. figure 1 comprises an air sampling module 3, an air compression module 5, an air orientation module 7, a heat exchange module 9, a cooling module 10, a thermal recovery module 20, a turbine 30 and an air conditioning module 40 of the pressurized cabin of the aircraft.

Air sampling module 3

The air sampling module is configured to collect ambient air outside the aircraft. The air sampling module 3 comprises one or more external ambient air inlets, preferably a single air inlet, for example of the dynamic air inlet type. An air inlet is said to be dynamic (as opposed to a static air inlet) when it is capable of transforming the kinetic energy of the captured air into pressure (stop pressure or dynamic pressure). Such a dynamic air intake may be that of an auxiliary power unit of the aircraft (Auxiliary Power Unit or APU in English). In an alternative embodiment, the air sampling module may consist of one or more controllable air bleed valves.

Air compression module 5

The air compression module 5 comprises at least one compressor, which may for example be the charge compressor of an auxiliary power unit of the aircraft. Such a unit usually comprises a charge compressor 5, and a turbomachine comprising a motor or a generator 35 and a turbine 30. The charge compressor 5 is configured to receive the flow of air F1 taken by the sampling module 3, the compressing and conveying the flow of compressed air F2 to the air guidance module 7.

Air orientation module 7

The air orientation module 7, for example a two-way valve, is configured to guide the flow of compressed air F2 to the heat exchange module 9 or to the thermal recovery module 20. air orientation 7 comprises means for measuring the temperature of the compressed air flow F2 coming from the air compression module 5 and means for comparing the measured value with a reference value corresponding to the level required at the input of the cabin air conditioning module 40. The air orientation module 7 is then configured to direct the flow of compressed air F2 to the heat exchange module 9 and then to cool it when the measured temperature of the compressed air is greater than that required level input air conditioning module 40. The air orientation module 7 is also configured to direct the flow of compressed air to the heat recovery module 20 to warm it r when the measured temperature of the compressed air is lower than the required level at the input of the air conditioning module 40.

Heat exchange module 9

The heat exchange module 9 comprises at least one heat exchanger configured to allow a heat exchange between the compressed air stream F2 received from the air orientation module 7 and a flow of gaseous fluid F5 from the module of cooling 10.

Cooling module 10

The cooling module 10 is configured to receive the air flow F3 from the air orientation module 7 and having passed through the heat exchange module 9 and to cool said received stream F3. As illustrated by figure 2 , the cooling module comprises a condenser 12, a water extractor 13, a cooler 14, a cryogenic fluid reservoir 15, for example liquid nitrogen pressurized to 10 bar, a first control valve 16 disposed between the reservoir of cryogenic fluid 15 and the condenser 12 and a second control valve 17 disposed between the cryogenic fluid reservoir 15 and the cooler 14. The condenser 12 is configured to receive a flow of air to be cooled, for example a compressed air flow. potentially humid at a temperature up to 100 ° C at the cabin pressure, for example about 0.8 bar. The condenser 12 is also configured to condense the water vapor contained in the received compressed air flow while avoiding its icing by maintaining a positive temperature at its output. The water extractor 13 is configured to extract the water from the air stream, condensed by the condenser 12, whose water flow F8 can then be, for example, removed or injected into a water circuit. of the aircraft. The cooler 14 is configured to cool the flow of dry air received from the water extractor 13 from cryogenic fluid received from the tank 15 through the second control valve 17 and to convey the flow of cold and dry air. F4 obtained to the air conditioning module 40 of the cabin. The liquid cryogenic fluid stored in the tank is thus used both by the condenser 12 and both by the cooler 14. The cooling fluid passed in gaseous form after the heat exchanges made at the condenser 12 and the cooler 14 is recycled by being conveyed to the heat exchange module 9 to cool the flow of compressed air F2 passing through the heat exchange module 9 and coming from the air orientation module 7.

Heating module 20

The heating module 20 may be in the form of a thermal recuperator, for example disposed in the exhaust of the auxiliary power unit (APU). The heating module 20 is configured for, in a first mode of operating, heat the airflow F2 received from the air orientation module 7 and then route it to the air conditioning module 40 of the cabin and, in a second operating mode, heat the flow of cooling fluid gas F5 received from the heat exchange module 9 and send it to the turbine 30. A bypass path of this heating module may be provided to regulate the heating thermal energy of the air flow F2.

Turbine 30

The turbine 30 is configured to receive a flow of gaseous fluid from the heating module 20. The mechanical energy produced by the turbine 30 from the stream of gaseous fluid received can be, for example, injected into the transmission box of the auxiliary power unit (APU), or used to drive an alternator, or for any other possibly more appropriate use. The gas stream at the outlet F7 can still be used to cool the engine bay of the aircraft and / or render inert the atmosphere, if the fluid is nitrogen gas for example.

Air conditioning module of the pressurized cabin of the aircraft

The air conditioning module 40 comprises a mixer (not shown) configured to receive the cooled air flow F4 of the cooling module 10 and mix it with air from the cabin so as to provide the cabin with a flow of air at the desired setting temperature.

The system according to the invention may also comprise means for regulating the cabin pressure (not shown) and control means configured to control one or all of the modules of the system (air sampling module, air compression, air orientation, cooling, air conditioning heating turbine ...).

IMPLEMENTATION OF THE SYSTEM ACCORDING TO THE INVENTION

In a first step E1, the air sampling module 3 withdraws ambient ambient air and conveys the ambient air stream taken F1 to the air compression module 5.

In a step E2, the air compression module 5 compresses the withdrawn air F1 and sends the flow of compressed air F2 to the air orientation module 7.

In a step E3, the air orientation module 7 determines whether the temperature of the compressed air flow F2 is greater or less than a reference value associated with the level required at the input of the air conditioning module 40.

When the temperature of the compressed air flow is greater than the reference value, the air orientation module 7 conveys, in a step E4, the flow of compressed air F2 to be cooled to the heat exchange module 9 The flow of compressed air F2 then passes through the heat exchange module 9, in which it undergoes a first cooling, during a step E5, with a gaseous fluid F5 from the cooling module 10. The air flow compressed F3 is then conveyed to the cooling module 10 in which it undergoes a second cooling during a step E6.

More precisely, the flow of compressed air F3 passes through the condenser 12, in a step E61, during which the water vapor possibly present in the air stream is condensed. The condenser 12 uses the cryogenic fluid received, through the first valve 16, the cryogenic fluid reservoir 15 to reduce the temperature of the air flow to a slightly positive temperature, for example 2 ° C so as to allow the condensation water vapor without icing. The gaseous fluid F5 produced by the heat exchange between the air flow and the cryogenic fluid is then conveyed to the heat exchange module 9.

The water is then extracted from the air stream, in a step E62, by the water extractor 13 and then the air flow is conveyed to the cooler 14 which then uses, in a step E63, the cryogenic fluid received, through the second valve 17, to decrease the temperature of the dry air flow to the required temperature level at the input of the air conditioning module 40, for example -15 ° C. The gaseous fluid produced by the heat exchange between the air flow and the cryogenic fluid is also conveyed to the heat exchange module 9.

The cold and dry air flow F4 is then conveyed, in a step E7 to the air conditioning module of the cabin 40. The desired cabin temperature can then be obtained by means of the mixer of the air conditioning module 40. Moreover, the means for regulating the pressure in the cabin make it possible to maintain the cabin under pressure, for example at 0.8 bar.

The gaseous fluid F5 resulting from the heat exchanges in the condenser 12 and in the cooler 14 is conveyed via a feedback loop, during a step E8, to the heat exchange module 9 where it serves to perform a first cooling compressed air flow F2 from the air orientation module 7.

Once the heat exchange has been carried out in the heat exchange module 9, the flow of gaseous fluid is conveyed to the heating module 20 which increases its temperature, in a step E9, before sending it to the turbine 30 of the APU during a step E10. The turbine 30 can then use the flow of gaseous fluid F6 to, for example, power a generator and produce electricity.

When the temperature of the flow of gaseous fluid F7 is less than a reference value, for example about thirty degrees Celsius, the flow can serve to cool the engine bay of the aircraft and / or to render the atmosphere inert in a step E11.

When the temperature of the compressed air flow F2 is lower than the reference value, the air orientation module 7 conveys, in a step E12, the flow of compressed air F2 to be heated to the heating module 20.

The heating module 20 then increases the temperature of the air flow during a step E13 and then conveys it to the air conditioning module 40 of the cabin during a step E14. The desired temperature in the cabin can then be obtained through the mixer of the air conditioning module 40.

Of course, in a simplified embodiment of the system according to the invention, the heat exchange module 9 could be absent and the compressed air flow F 2 could then be conveyed directly from the air orientation module 7 to the module cooling 10.

The system according to the invention therefore makes it possible to compress a flow of air taken from the ambient air outside the aircraft to a value close to that of the pressure required in the cabin, for example with a compression ratio of 3 or 4, which does not require a lot of energy. The cooling module then allows the flow to be cooled to lower the temperature to the level required at the input of the air conditioning module of the cabin.

Claims (7)

1. Air conditioning system for a pressurised cabin of an aircraft, said system (1) comprising an air withdrawal module (3) configured for withdrawing ambient air from outside the aircraft, an air compression module (5) configured for compressing the withdrawn air flow (F1) and an air cooling module (10), characterized in that the air cooling module (10) is configured for cooling the compressed air flow (F2, F3) by means of a cryogenic fluid, the cooling module (10) comprising a condenser (12) for condensing water from the air flow, a water extractor (13) for extracting said water, a cooler (14) for cooling the dry air flow emitted by the water extractor (13) and a tank (15) for a cryogenic fluid, by means of which fluid the water from the air flow is condensed in the condenser (12) and the dry air emitted by the extractor is cooled in the cooler (14).
2. System according to claim 1, wherein the cooling module (10) is self-contained.
3. System according to either of the preceding claims, wherein the cooling module (10) is configured for delivering a gaseous fluid for supply to a turbine (30) by means of the cryogenic fluid.
4. System according to any of the preceding claims, said system (1) comprising a heating module (20) configured for receiving, from a thermal exchange module (9), a flow of gaseous fluid (F5) and for routing said flow towards a turbine (30), or for receiving, from the air orientation module (7), a compressed air flow (F2) to be reheated and for routing said flow towards an air conditioning module (40) of the cabin of the aircraft.
5. System according to any of the preceding claims, said system (1) comprising a thermal exchange module (9) arranged between the air compression module (5) and the cooling module (10) and configured for cooling the compressed air flow (F2) received from the air compression module (5) by means of the flow of gaseous fluid (F5) delivered by the cooling module (10), and for routing, on the one hand, the compressed air flow thus cooled (F3) towards the cooling module (10) and, on the other hand, the flow of gaseous fluid (F5) towards the heating module (20).
6. System according to any of the preceding claims, said system (1) comprising an air flow orientation module (7) arranged between the compression module (5) and the cooling module (10) and configured for orienting the air flow (F2) compressed by the air compression module (5) towards the air cooling module (10) when the temperature of the compressed air is greater than the temperature required at the inlet of an air conditioning module (40) of the cabin, or towards the heating module (20) when the temperature of the compressed air is lower than the temperature required at the inlet of an air conditioning module (40) of the cabin.
7. Aircraft characterised in that it comprises a system according to any of claims 1 to 6.

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